Hybrid Integrated Circuits (HIC) often include active chips, such as Integrated Circuit (IC) chips, or some other elements or devices which during operation either generate heat or are subjected to heat generated by other elements of the HIC. Some of the devices may be susceptible to heat-induced changes in operating characteristics or other heat-induced damage, such as warping, separation, wire breakage, fracture, etc. These adverse effects may become more pronounced in circuits, in which the elements are densely clustered. Thus, it is desirable to remove excess heat from at least some of the individual elements of the HICs by providing them with "heat-sinks" of a high heat-conductivity metal to pick-up and transfer the heat away from these elements. In some instances, it may be desirable to remove a variable amount of heat. For example, when an element or a device is programed to operate at a certain temperature or when the circuitry is in a cold environment, removal of an excess amount of heat could adversely affect the operational characteristics of the element or device. Therefore, it may be desirable to remove heat only when a certain temperature level is reached which is in excess of the normal operating temperature of the element or device.
U.S. Pat. No. 4,408,220 issued to A. D. Calabro on Oct. 4, 1983 discloses a heat-dissipator (a heat sink) structure including top and bottom metal plates interconnected by an intermediate metal section. This structure is formed so as to be slidably mounted on an IC package which is mounted on a support base, such as a printed circuit board. The top plate of the heat-sink is resiliently connected to the intermediate section and when in position contacts a heat spreader plate common to a number of such heat-sinks. However, with further miniaturization and automation of manufacture and assembly, such a mechanically secured heat-sink may prove difficult to use. Furthermore, that heat sink is not programmed for variable heat transfer from the IC to the heat spreader.
It is, thus, desirable to provide HICs with a heat-sink attached to an element such as a chip or some other device and capable of transferring varied amounts of heat energy to a heat spreader or dissipator in response to a correspondingly varied temperature of the element or device or environment so as to stabilize the operating temperature of the HIC.